1. Field of the Invention
The invention relates to a key module and a method for controlling the same, more particularly to a key module having light-indicating functionality and a method for controlling the key module.
2. Description of the Related Art
For an electronic device that requires to be operated in the dark, such as a projector, the design of providing keys with indicating lights facilitates clear identification of the locations of and functions associated with the keys, thereby facilitating easy operation of the electronic device in the dark.
As shown in FIG. 1, a conventional key module 9 having light-indicating functionality and adapted for use in a conventional electronic device (not shown) includes a microprocessor 90, a key set 91 including a plurality of keys 911, a drive circuit 92, and a backlight unit 93. The backlight unit 93 includes a plurality of light emitting components 931 that are respectively disposed adjacent to the keys 911 for providing indicating light around the keys 911 such that a user clearly sees and locates the keys 911 in the dark.
There are two conventional methods for designing the operation of providing the indicating light for the keys 911. In the first conventional method, as long as the microprocessor 90 is active (e.g., operating in the projecting mode), the microprocessor 90 provides a control signal to the drive circuit 92, commanding the drive circuit 92 to provide a drive signal to continuously turn on the backlight unit 93 such that the light emitting components 931 continuously provide the indicating light, regardless of whether a key 911 is pressed. In the second conventional method, the microprocessor 90 provides a control signal to the drive circuit 92, commanding the drive circuit 92 to transmit a drive signal to turn on the backlight unit 93 such that the light emitting components 931 provide the indicating light whenever one of the keys 911 is pressed.
However, in both of the conventional methods, the drive circuit 92 drives all of the light emitting components 931 in the backlight module 93 at the same time, such that all of the light emitting components 931 provide the indicating light whenever the microprocessor 90 provides a control signal to the drive circuit 92. Thus, the following shortcomings are present in the conventional methods:
1. Whether only one of the keys 911 or multiple ones of the keys 911 are pressed, all of the light emitting components 931 of the backlight unit 93 provide the indicating light, increasing the overall power consumption of the key module 9, thereby resulting in failure to comply with the energy saving requirement for a green product.
2. Individual keys 911 are not provided with corresponding light emitting components 931 that provide the indicating light only when the corresponding key 911 is pressed, thereby resulting in the user being unable to confirm which key 911 was actually pressed.
3. In the case where the backlight unit 93 is turned on such that all of the light emitting components 931 constantly provide the indicating light while the microprocessor 90 is active, a lot of energy is wasted.